In integrated circuit applications, more and more functions are integrated into products. For example, different functional elements such as 3G video elements, WiFi elements, Bluetooth elements, and audio/video elements may need to be integrated together to form an application.
In conventional integration schemes, different components are bonded to an interposer, which is further bonded to a package substrate. For example, in mobile applications, a power management integrated circuit die, a transceiver die, and a multi-layer ceramic capacitor may be bonded using this scheme. The resulting package is typically very thick and large in area. In addition, since the various components that are bonded to the interposer are connected to the interposer through many electrical connections, the pitch of the electrical connections of the interposer need to be very small, and sometimes as small as about 40 nm to 50 nm. Such small pitch requires the interposer to use micro-bumps (u-bumps), whose formation still faces technical challenges.